,-------------------.                                
                                 |x                  |                                
                                 |-------------------|                                
                                 |class  = data.frame|                                
                                 |typeof  = list     |                                
                                 |mode  = list       |                                
                                 |length = 4         |                                
                                 |__attributes__     |                                
                                 |.names = X c b n   |                                
                                 |.row.names = 1 2 3 |                                
                                 `-------------------'                                
                                                                                      
                                                                                      
,-----------------.  ,-------------------.   ,-----------------.   ,-----------------.
|X                |  |c                  |   |b                |   |n                |
|-----------------|  |-------------------|   |-----------------|   |-----------------|
|class  = integer |  |class  = character |   |class  = logical |   |class  = integer |
|typeof  = integer|  |typeof  = character|   |typeof  = logical|   |typeof  = integer|
|mode  = numeric  |  |mode  = character  |   |mode  = logical  |   |mode  = numeric  |
|length = 3       |  |length = 3         |   |length = 3       |   |length = 3       |
`-----------------'  `-------------------'   `-----------------'   `-----------------'